Wednesday, 26 April 2017

Paper to Pixel to Paper Again: Part 14

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A guide to creating the best looking line art in print in the new digital print world

Part 14
Production Negative Adjustment


This is the fourteenth installment of Paper to Pixel to Paper Again, a series that explains (in an overly thorough manner) the how-to's of preparing line art (and later in the series, color art!) for print.

And as always, if you have any questions, please let me know in the comments!


In the last installment of this column, we discussed working with production negatives, the film elements that were generated in order to create printing plates in previous, pre-digital printing processes. 

As I mentioned in that column, there's a huge range of possible qualities to these production negatives. The best of these photographic negatives can look almost indistinguishable from making fresh scans of original art. The worst have filled-in or burned off elements that can't be recovered, or had gross manipulations during the photography, or chemical spills or camera errors or other problems. But for this installment, we'll only address how to work with the best of these elements.

Okay, as of our previous installment, we've cut the negatives off of the vacuum-frame flats and cleaned them, and scanned them at 1200 ppi. Now let's take a look.

This is a page from High Society, scanned prior to my coming on board with the work.

I can tell just looking at the dot-tone on the Cerebus figures that this is an uncalibrated scan, i.e. the density of the image is too dark, and unrepresentative of the original artwork. This is not surprising, as most scanning software is not really calibrated to scan information-rich, dark and dense images. Fortunately, there is an easy fix for this, that involves looking at the density of the Cerebus dot tone (which, unless it was adjusted during photography, was usually some density of 30 percent).

Let's zoom in on the bottom area of the page, where we have both Cerebus figures (i.e. dot-tone) and the denser cross-hatching at the bottom of the page.

Now I'm going to hit Ctrl-L to bring up the Levels command. Once it's open, I grab the Mid Point arrow (i.e. the Gamma/exposure control) and move it to the left until the Cerebus tone has opened up and starts looking like a 30 percent tone again.

And here's our result. 

Well, would ya look at that? In addition to thinning out everything uniformly, our correction is bringing out detail that was hidden/filled in in the initial image. Most of this detail is wanted—the white detail in the dense areas of cross-hatching, for instance. But some of it will need to be cleaned, as it's unintentional "detail" brought out by our adjustment.

For instance?

Mysterious shapes around the contours of Cerebus' ears. (Not actually so mysterious if you view the image in reverse, how it actually appears on the negative. Some kindly person at the printer (possibly the "stripper") has removed the visible Exacto-blade cut lines from the edges of Cerebus's tone with an exacto knife of their own, scraping the emulsion off of the clear plastic carrier film. 

In this same category, you can now see the bottom of the image was once held in place on the flats with tape that actually overlapped the image. This will also need to be adjusted.

But all of this is for another stage, so let's put it off for a bit and take a look at a negative from later in the book instead.

Here's a page from later in Church & State II. Notice that the tone is similarly dense to the earlier example, and needs a similar type of Gamma adjustment. Some of the stripping has also been removed in this example, leaving the "chop" on the top of the page visible and parts of the bottom of the page exposed.

This time we're going to make our Gamma adjustment, then make a new Photoshop "Action" for upscaling and sharpening our negatives.

I'm going to zoom in and concentrate on the first panel (the medium shot of Cerebus) for calibrating the page, as the other figures that have finer tonelook like they've been manipulated photographically to adjust the darkness of the tone (and thus to make it less prone to fill-in on press. (How I know this?  I'll go into it on a later installment)

Anyway, here's the medium-density tone figure.

I bring that Gamma control way, waaay down, and I end up bringing up the black point just a wee bit as well (as you can see by the histogram, there's nothing on the far end of it, so I'm not clipping anything by bringing it up.

Anything else exciting we brought up with that adjustment?

Nothing too exciting, besides lots more detail, especially in the dense areas of hatching and white-on-black areas. Also some unintentional information, such as the edges of Roxanne Starr's lettering bubbles, pasted onto the artwork late in the process.

Next week: We sharpen some negatives! Woo-hoo!


Carson Grubaugh said...

So crazy that all that stuff is basically just hidden in there! Must be pretty interesting seeing all of the evidence emerge.

Sean R said...

Wait till you see the damaged ones! Yeah, it's an interesting phenomenon. Working on the negs definitely feels like a treasure hunt (as opposed to working on the original artwork w tone degredation, which sometimes feels like being a digital hairdresser or something...)

Margaret said...

Thanks for sharing these hidden gems with us Sean. I enjoy these behind the scenes looks at the restoration efforts. I work at a company that uses mylar films that have emulsion on them, so seeing the things that the printer can do to them is interesting.